Prevalence of mental disorders

The prevalence of mental disorders has been studied around the world, providing estimates on how common mental disorders are. Different criteria or thresholds of severity have sometimes been used.

National and international figures are typically estimated by large-scale surveys of self-reported symptoms up to the time of assessment; sometimes a figure is calculated for the occurrence of disorder in the week, month or year prior to assessment–a point or period prevalence; sometimes the figure is for a person's lifetime prior to assessment–the so-called lifetime prevalence.